1. Field of the Invention
The invention concerns cosmetic sunscreen compositions delivering UV protection and also soft focus properties.
2. The Related Art
Ultraviolet radiation can be damaging to skin. Immediate damage may be in the form of erythema. More long term is the concern of initiating cancerous growth. For these reasons, photoprotective agents known as sunscreens have been incorporated into cosmetic products.
Facial cosmetics desirably deliver not only photoprotection but also function to enhance overall skin appearance. Most persons have facial imperfections. These may include uneven tone, enlarged pores, fine lines and wrinkles.
Soft focus is an effect which can hide imperfect skin. Incoming light is distorted by scattering (lensing). Particulate components of the cosmetic operate as lenses to bend and twist light into a variety of directions.
U.S. Pat. No. 5,997,890 (Sine et al.), U.S. Pat. No. 5,972,359 (Sine et al.), and U.S. Pat. No. 6,174,533 B1 (SaNogueira, Jr.) are all directed to topical compositions to provide good coverage of skin imperfections. The solution proposed by these documents is the use of a metal oxide with a refractive index of at least about 2 and a neat primary particle size of from about 100 to about 300 nm. Preferred particulates are titanium dioxide, zirconium oxide and zinc oxide.
U.S. Patent Application 2005/0163813 A1 (Kosbach et al.) reports use of fumed alumina particles for enhancing the soft-focus effect of certain cosmetic compositions.
Organic sunscreen agents can interfere with soft focus properties of a cosmetic formulation. This is especially noticeable with formulas having relatively high levels of organic phase and/or emulsions with continuous oil phase characteristics. Consequently, there is a challenge to provide cosmetics with a strong soft focus effect while maintaining a relatively high degree of photoprotective benefits for the composition.